Asthma and lung function 20 years after wheezing in infancy: results from a prospective follow-up study

Lung function, allergic sensitization and asthma in school-aged children after viral-coinfection bronchiolitis

Our main objective was to compare the lung function, the rate of allergic sensitization and the prevalence of asthma at 7–9 years in children hospitalized for bronchiolitis with viral coinfection versus single viral infection. Observational study in children with previous bronchiolitis and current age 7–9 years. Clinical data were collected. Fraction of exhaled nitric oxide (FeNO) determination, spirometry and skin prick test for common aeroallergens were performed. A total of 181 children hospitalized for bronchiolitis (40 coinfections and 141 single infections), with median age of 8.3 years (IQR:7.5–9.1) were included. Single-HRV-infections showed lower basal FEV1(%) than coinfections (p = 0.04) and lower z-score FEV1 than single-RSV-infections (p = 0.04) or coinfections (p = 0.02). Also, single-HRV-infections had lower post-bronchodilator FEV1(%) and z-score FEV1 values than coinfections (p = 0.03 and p = 0.03). Single-HRV-bronchiolitis was an independent risk factor for FEV1 < 80% (p = 0.007). FeNO value > 25 ppb was detected in 21(12.5%) cases, without differences between viral groups (p = 0.768). The prevalence of allergic sensitization was similar in coinfections (31.4%) versus single infections (38.7%), (p = 0.428). The highest frequency of allergic rhinitis was observed in single-HRV patients (p = 0.004). The respiratory morbidity at 7–9 years of coinfected patients was similar to the single-HRV ones. In contrast, the likelihood of current asthma was up to 5 times higher in RSV/HRV coinfections than in the single-RSV-infections ones (p = 0.012). The respiratory morbidity at 7–9 years of age after severe bronchiolitis is significantly higher in single-HRV or viral coinfection patients that in single-RSV ones. Single-HRV-bronchiolitis is independently associated with lower lung function at school-age.

An increased asthma risk continued until young adulthood after early-childhood hospitalisation for wheezing

AIM

The aim of this cohort study was to evaluate doctor-diagnosed and self-reported asthma in young adults after early-childhood hospitalisation for wheezing.

METHODS

In this prospective-controlled follow-up, questionnaires were sent to 95 subjects aged 24-28 years, who had been hospitalised for their first episodes of wheezing under 24 months of age. Fifty-eight cases and 100 controls returned the questionnaires.

RESULTS

The risk of doctor-diagnosed asthma was 2.14-fold (95% confidence interval 0.61-7.41), and the risk of self-reported asthma 2.39-fold (1.14-4.99) in cases compared to controls. The increased risk of self-reported asthma remained as statistically significant in analyses adjusted for current smoking, overweight and allergic rhinitis. Study subjects presented with wheezing symptoms, use of bronchodilators and inhaled corticosteroids, and with seasonal symptoms presumptive for allergic rhinitis during the last 12 months, more often than controls. The identification of a respiratory syncytial virus or rhinovirus during hospitalisation in early childhood was not anymore associated with asthma risk in adulthood. As expected, previous asthma during early childhood was a strong risk factor for asthma in young adulthood.

CONCLUSION

In this controlled questionnaire study, early-childhood hospitalisation for lower respiratory infection with wheezing was an independently significant risk factor of asthma in young adults.

Association between early bronchiolitis and the development of childhood asthma: a meta-analysis

OBJECTIVE

Early life bronchiolitis has been hypothesised to be associated with the subsequent risk of persistent wheezing or asthma. However, the link remains controversial. The objective of our study was to evaluate the association between bronchiolitis before 2 years of age and the late-onset wheezing/asthma.

DESIGN

Systematic review and meta-analysis.

METHODS

PubMed, Embase and Web of Science databases were systematically searched for studies published between 1955 and January 2020. Meanwhile, we also checked through the reference lists of relevant articles to see whether these references included reports of other studies that might be eligible for the review. Cohort and case-control studies assessing the association between early-life bronchiolitis and late-onset wheezing/asthma were included in this meta-analysis. Data were extracted by two independent reviewers. Results were pooled using a random-effects model or fixed-effects model according to the heterogeneity among studies.

RESULTS

32 original articles with 292 844 participants, which met the criteria, were included in this meta-analysis. Bronchiolitis before 2 years of age was associated with an increased risk of subsequent wheezing/asthma (relative risk=2.46, 95% CI 2.14 to 2.82, p<0.001). After categorising studies into different groups based on age at the end of follow-up, geographical region and study quality, the association still remained significant.

CONCLUSIONS

The meta-analysis indicates an association between bronchiolitis before 2 years of age and the wheezing/asthma in later life. Well-designed and highly standardised prospective studies that better address bias due to potential confounding factors are needed to validate the risk identified in our meta-analysis.PROSPERO registration numberCRD42018089453.

Lung function trajectories and bronchial hyperresponsiveness during childhood following severe RSV bronchiolitis in infancy

BACKGROUND

Children with severe respiratory syncytial virus (RSV) bronchiolitis in infancy have increased risks of asthma and reduced lung function in later life. There are limited studies on the longitudinal changes of lung function and bronchial hyperreactivity from early to late childhood in infants hospitalized for RSV bronchiolitis.

METHODS

In a prospective cohort of 206 children with their first episode of RSV-confirmed bronchiolitis in the first year of life, 122 had spirometry performed at least twice between 5-16 years of age. Methacholine bronchoprovocation was available in 127 and 79 children at 7 and 12 years of age, respectively. Longitudinal changes in FEV₁ , FVC, and FEV₁ /FVC z-scores and methacholine PC₂₀ were analyzed.

RESULTS

55% of the study cohort (N = 122) were male, and 55% were Caucasian. During follow-up, longitudinal changes in z-scores for pre- and post-bronchodilator FEV₁ (P < .0001) FVC (P < .0001) and FEV₁ /FVC (P < .0001 for pre- and 0.007 for post-bronchodilator) from age 5 to 10-16 years were observed. Declined lung function in late childhood was significantly associated with gender, physician diagnosis of asthma, and allergic sensitization. PC₂₀ geometric mean increased from 0.28 mg/mL at 7 years to 0.53 mg/mL at 12 years of age, and the frequency of abnormal bronchial hyperreactivity decreased from 96% to 78% (P = .0003).

CONCLUSIONS

Following severe RSV bronchiolitis, there appear to be significant longitudinal changes in pre- and post-bronchodilator lung function during childhood. The study has several limitations including significant dropouts and the lack of a control group and post-bronchodilator measurements. Bronchial hyperreactivity is common in children following severe RSV bronchiolitis; however, it appears to decrease as they enter late childhood.

Respiratory sequelae and quality of life in children one-year after being admitted with a lower respiratory tract infection: A prospective cohort study from a developing country

INTRODUCTION

Respiratory tract infections in children can result in respiratory sequelae. We aimed to determine the prevalence of, and factors associated with persistent respiratory sequelae 1 year after admission for a lower respiratory tract infection (LRTI).

METHODOLOGY

This prospective cohort study involved children 1 month to 5-years-old admitted with an LRTI. Children with asthma were excluded. Patients were reviewed at 1-, 6-, and 12-months post-hospital discharge. The parent cough-specific quality of life, the depression, anxiety, and stress scale questionnaire and cough diary for 1 month, were administered. Outcomes reviewed were number of unscheduled healthcare visits, respiratory symptoms and final respiratory diagnosis at 6 and/or 12 month-review by pediatric pulmonologists.

RESULTS

Three hundred patients with a mean ± SD age of 14 ± 15 months old were recruited. After 1 month, 239 (79.7%) returned: 28.5% (n = 68/239) had sought medical advice and 18% (n = 43/239) had cough at clinic review. Children who received antibiotics in hospital had significantly lower total cough scores (P = .005) as per the cough diary. After 1 year, 26% (n = 78/300) had a respiratory problem, predominantly preschool wheezing phenotype (n = 64/78, 82.1%). Three children had bronchiectasis or bronchiolitis obliterans. The parent cough-specific quality of life (PCQOL) was significantly lower in children with respiratory sequelae (P < .01). In logistic regression, the use of antibiotics in hospitals (adjusted odds ratio, 0.46; P = .005) was associated with reduced risk of respiratory sequelae.

CONCLUSION

In children admitted for LRTI, a quarter had respiratory sequelae, of which preschool wheeze was the commonest. The use of antibiotics was associated with a lower risk of respiratory sequelae.

Special Considerations in Preschool Age

The diagnosis of asthma can be particularly difficult in young children, in whom wheezing is not always synonym with asthma. It is also difficult to predict which preschool children with wheeze will go on to be true asthmatics. In this chapter, we will characterize preschool wheezing and asthma and discuss early risk factors for the development of severe asthma. We will also review risk factors for severe acute wheezing in young children. Finally, we will describe the natural history and prognosis of wheezing and some of the attempts at early identification of children who will develop severe asthma.

Cost effectiveness of vitamin c supplementation for pregnant smokers to improve offspring lung function at birth and reduce childhood wheeze/asthma

OBJECTIVE

To determine the implications of supplemental vitamin C for pregnant tobacco smokers and its effects on the prevalence of pediatric asthma, asthma-related mortality, and associated costs.

STUDY DESIGN

A decision-analytic model built via TreeAge compared the outcome of asthma in a theoretical annual cohort of 480,000 children born to pregnant smokers through 18 years of life. Vitamin C supplementation (500 mg/day) with a standard prenatal vitamin was compared to a prenatal vitamin (60 mg/day). Model inputs were derived from the literature. Deterministic and probabilistic sensitivity analyses assessed the impact of assumptions.

RESULT

Additional vitamin C during pregnancy would prevent 1637 cases of asthma at the age of 18 per birth cohort of pregnant smokers. Vitamin C would reduce asthma-related childhood deaths and save $31,420,800 in societal costs over 18 years per birth cohort.

CONCLUSION

Vitamin C supplementation in pregnant smokers is a safe and inexpensive intervention that may reduce the economic burden of pediatric asthma.

Asthma and lung function in adulthood after a viral wheezing episode in early childhood

BACKGROUND

Viral aetiology of infection has a significant role in the long-term outcome of early-childhood wheezing.

OBJECTIVE

This study examines asthma and lung function in adulthood after early-childhood wheezing induced by respiratory syncytial virus (RSV) and rhinovirus (RV).

METHODS

A total of 100 children were hospitalized for a wheezing episode at less than 24 months of age from 1992 to 1993 in Kuopio University Hospital (Finland). Adenovirus, influenza A and B virus, parainfluenza (1-3) virus, and RSV were tested on admission using antigen detection and antibody assays, and RSV and RV were tested by polymerase chain reaction (PCR). In 2010, 49 cases and 60 population controls attended a follow-up study, which included spirometry with bronchodilation test and fractionally exhaled nitric oxide (FE_NO ) measurements.

RESULTS

Current asthma was present in 64% of the cases with RV-induced wheezing (OR 17.0 [95%CI 3.9-75.3] vs controls), in 43% of the cases with RSV-induced wheezing episode (6.1 [1.5-24.9] vs controls), and in 12% of the controls. The RV group showed significantly higher mean FE_NO values than the RSV group and controls. RV-positive cases had lower MEF50 before bronchodilation and higher MEF50, FEV1, and FEV1/FVC bronchodilation responses than controls. RSV-positive cases had lower FVC than controls before bronchodilation.

CONCLUSION

Cases with RV- and RSV-induced early-childhood wheezing had increased risk for asthma in adulthood, and RV-positive cases had significantly higher FE_NO values than RSV-positive cases and controls. Compared to controls, RV-positive cases showed more bronchial reactivity, and RSV-positive cases showed lower FVC before bronchodilation in lung function testing.

CLINICAL RELEVANCE

Children with RV- or RSV-induced wheezing in early childhood have an increased risk for asthma and lung function abnormalities in adulthood.

[Recurrent wheezing: prevalence and associated factors in infants from Buenos Aires City, Argentina]

BACKGROUND

The episodes of bronchial obstruction at early age constitute a frequent problem in Pediatrics. The aim of this study was to evaluate the prevalence of recurrent wheezing in infants in Buenos Aires City, as well as to identify any associated factors.

METHODS

Cross-sectional study performed from 2011 to 2012 in the Children Hospital Ricardo Gutiérrez, Buenos Aires City, as part of the International Study of Wheezing in Infants. A validated questionnaire was applied to parents of infants aged between 12 and 15 months. The prevalence of wheezing, mostly the recurrent episodes (three or more), and their probable associated factors were evaluated. Data were statistically analyzed with χ², Fisher's test, binary and logistics multiple regression analysis. The significance level was 0.05.

RESULTS

Over 1063 infants, 58.9% (confidence interval (CI) 95% 55.9-61.9) presented at least one episode of wheezing and 26.3% (CI95% 23.8-29.9) three or more episodes (recurrent wheezing). Risk factors associated to wheezing were male gender (p=0.001), six or more episodes of cold during the first year of life (p <0.0001), age at first cold <4 months (p <0.0001); pneumonia (p <0.0001) and smoking during pregnancy (tobacco) (p=0.01). For recurrent wheezing, risk factors we considered as six or more episodes of cold during the first year of life (p <0.0001), early (< 4 month of age) onset wheezing (p <0.0001) and nocturnal wheezing (p <0.0001).

CONCLUSIONS

The prevalence of recurrent wheezing among infants in Buenos Aires Ciy was high (26.3%). Some identified associated factors can be preventable.

A systematic review of early life factors which adversely affect subsequent lung function

It has been known for many years that multiple early life factors can adversely affect lung function and future respiratory health. This is the first systematic review to attempt to analyse all these factors simultaneously. We adhered to strict a priori criteria for inclusion and exclusion of studies. The initial search yielded 29,351 citations of which 208 articles were reviewed in full and 25 were included in the review. This included 6 birth cohorts and 19 longitudinal population studies. The 25 studies reported the effect of 74 childhood factors (on their own or in combinations with other factors) on subsequent lung function reported as percent predicted forced expiration in one second (FEV₁). The childhood factors that were associated with a significant reduction in future FEV₁ could be grouped as: early infection, bronchial hyper-reactivity (BHR) / airway lability, a diagnosis of asthma, wheeze, family history of atopy or asthma, respiratory symptoms and prematurity / low birth weight. A complete mathematical model will only be possible if the raw data from all previous studies is made available. This highlights the need for increased cooperation between researchers and the need for international consensus about the outcome measures for future longitudinal studies.

Long-term effects of pneumococcal colonization during early childhood wheezing

BACKGROUND

Bacterial colonization during wheezing in early childhood has been associated with short-term relapses of wheezing, but no study has addressed the effects of Streptococcus pneumoniae colonization on long-term outcome of wheezing. The aim of the present study was therefore to evaluate whether pneumococcal (PNC) colonization during the first wheezing episode in early childhood is a determinant of asthma, atopy or lung function in the long term.

METHODS

In 1981-82 83 infants were hospitalized for first wheezing episode at <24 months of age. PNC colonization was defined as positive nasopharyngeal aspirate for S. pneumoniae either in culture or antigen detection on hospital admission. Atopy and repeated wheezing or asthma were diagnosed on all follow-up visits from infancy until the age of 28-31 years. Spirometry was conducted at the ages of 8-10, 18-20 and 28-31 years.

RESULTS

PNC colonization was found in 25/83 infants (30%) during hospitalization for wheezing in infancy. PNC colonization was not associated with later atopy, repeated wheezing, asthma or lung function at any time during the 30 year follow up.

CONCLUSION

PNC colonization during the first wheezing episode in early childhood is not a determinant of subsequent wheezing or later asthma, atopy or lung function in childhood, adolescence or adulthood.

[Seasonality in asthma: Impact and treatments]

The role of seasons should be taken into account in the management of asthma. The environment varies between seasons and it is well documented that asthma is modulated by environment. Viruses cause asthma exacerbations peak, in winter, in adults while the peak is present in September in children. Allergens are probably a less powerful source of asthma exacerbation than viruses but pollen involvement in spring and summer and dust mites in autumn are indisputable. Air pollutants, present in summer during the hottest periods, are also highly involved in asthma exacerbations. Indoor air pollution, in winter, is also implicated in asthma disease. All these environmental factors are synergistic and increase the risk of asthma exacerbation. Therapies should be adapted to each season depending on environmental factors potentially involved in the asthma disease.

Long-term effects of pneumonia in young children

Each year an estimated 120 million episodes of pneumonia occur in children younger than 5 years of age, resulting in one million deaths globally. Within this age group the lungs are still developing by increasing alveoli numbers and airway dimensions. Pneumonia during this critical developmental period may therefore adversely affect the lung’s structure and function, with increased risk of subsequent chronic lung disease. However, there are few longitudinal studies of pneumonia in otherwise healthy children that extend into adulthood to help address this important question. Birth cohort, longitudinal, case-control and retrospective studies have reported restrictive and obstructive lung function deficits, asthma, bronchiectasis, and chronic obstructive pulmonary disease. In particular, severe hospitalised pneumonia had the greatest risk for long-term sequelae. Most studies, however, were limited by incomplete follow-up, some reliance upon parental recall, risk of diagnostic misclassification, and potential confounders such as nutrition, social deprivation, and pre-existing small airways or lungs. More long-term studies measuring lung function shortly after birth are needed to help disentangle the complex relationships between pneumonia and later chronic lung disease, while also addressing host responses, types of infection, and potential confounding variables. Meanwhile, parents of young children with pneumonia need to be advised about the importance of symptom resolution, post-pneumonia. In addition, paying attention to factors associated with optimising lung growth such as good nutrition, minimising exposure to air pollution, avoiding cigarette smoke, and decreasing the risk of preventable infections through good hygiene and having their children fully vaccinated should be emphasised. Finally, in the developing world and for disadvantaged communities in developed countries, public health policies leading to good quality housing and heating, hygiene, education, and improving socio-economic status are also essential.

A systematic review of predictive models for asthma development in children

BACKGROUND

Asthma is the most common pediatric chronic disease affecting 9.6 % of American children. Delay in asthma diagnosis is prevalent, resulting in suboptimal asthma management. To help avoid delay in asthma diagnosis and advance asthma prevention research, researchers have proposed various models to predict asthma development in children. This paper reviews these models.

METHODS

A systematic review was conducted through searching in PubMed, EMBASE, CINAHL, Scopus, the Cochrane Library, the ACM Digital Library, IEEE Xplore, and OpenGrey up to June 3, 2015. The literature on predictive models for asthma development in children was retrieved, with search results limited to human subjects and children (birth to 18 years). Two independent reviewers screened the literature, performed data extraction, and assessed article quality.

RESULTS

The literature search returned 13,101 references in total. After manual review, 32 of these references were determined to be relevant and are discussed in the paper. We identify several limitations of existing predictive models for asthma development in children, and provide preliminary thoughts on how to address these limitations.

CONCLUSIONS

Existing predictive models for asthma development in children have inadequate accuracy. Efforts to improve these models' performance are needed, but are limited by a lack of a gold standard for asthma development in children.

Low eosinophils during bronchiolitis in infancy are associated with lower risk of adulthood asthma

BACKGROUND

Infant bronchiolitis may be the first manifestation of asthma.

AIM

To evaluate the association of early-childhood risk or protective factors for asthma and lung function reduction in adults 30 years after bronchiolitis in infancy.

METHODS

Forty-seven former bronchiolitis patients attended the clinical study at the median age of 29.5 years, including doctoral examination and measurement of post-bronchodilator lung function with flow-volume spirometry. Data on early-life risk factors including blood eosinophil counts on admission for bronchiolitis and on convalescence 4-6 weeks after bronchiolitis were available.

RESULTS

Low blood eosinophil count <0.25 × 10E9/l on admission for bronchiolitis was a significant protective factor and high blood eosinophil count >0.45 × 10E9/l on convalescence was a significant risk factor for asthma in adulthood independently from atopic status in infancy. Parental asthma and high blood eosinophil count >0.45 × 10E9/l during bronchiolitis were significant risk factors for irreversible airway obstruction (FEV1/FVC ratio below the 5th percentile lower limit of normality after bronchodilation).

CONCLUSION

Our adjusted analyses confirmed that eosinopenia during infant bronchiolitis predicted low asthma risk and eosinophilia outside infection predicted high asthma risk up to the age of 28-31 years. Parental asthma and eosinophilia during bronchiolitis were recognized as risk factors for irreversible airway obstruction.

MLBCD: a machine learning tool for big clinical data

Background

Predictive modeling is fundamental for extracting value from large clinical data sets, or “big clinical data,” advancing clinical research, and improving healthcare. Machine learning is a powerful approach to predictive modeling. Two factors make machine learning challenging for healthcare researchers. First, before training a machine learning model, the values of one or more model parameters called hyper-parameters must typically be specified. Due to their inexperience with machine learning, it is hard for healthcare researchers to choose an appropriate algorithm and hyper-parameter values. Second, many clinical data are stored in a special format. These data must be iteratively transformed into the relational table format before conducting predictive modeling. This transformation is time-consuming and requires computing expertise.

Methods

This paper presents our vision for and design of MLBCD (Machine Learning for Big Clinical Data), a new software system aiming to address these challenges and facilitate building machine learning predictive models using big clinical data.

Results

The paper describes MLBCD’s design in detail.

Conclusions

By making machine learning accessible to healthcare researchers, MLBCD will open the use of big clinical data and increase the ability to foster biomedical discovery and improve care.

High risk of adult asthma following severe wheezing in early life

BACKGROUND

Severe wheezing in early life is associated with an increased risk of asthma during childhood and adolescence. The aim of the present follow-up was to investigate the asthma prevalence and risk factors for asthma in adulthood.

METHODS

We have prospectively studied asthma development in 101 children hospitalized due to severe wheezing before the age of 24 months. The cohort was re-investigated at a mean age of 27 years and tested for bronchial hyper-responsiveness and allergic sensitization. The response rate in adulthood was 81% (82/101). The results were compared with a population-based, age-matched control group (n = 1,210) recruited from the West Sweden Asthma Study.

RESULTS

Current doctor-diagnosed asthma was found in 37% (30/82) compared with 7% (82/1,210) in the control group. The risk of adult asthma in the cohort compared with the control group was increased 10-fold (adjusted OR 10.0, 95% CI 5.3-18.7), independently of allergic rhinitis, gender, smoking and heredity. Within the cohort, current allergy (aOR 9.6, 95% CI 3.0-31.2) and female gender (aOR 3.2, 95% CI 1.1-9.3) independently increased the risk of adult asthma. Females with current allergy had the highest risk of adult asthma (OR 29.4, 95% CI 5.0-173.3), compared with males without allergy. When separately adjusting for factors present at admission in early life within the cohort, a family history of asthma was a significant risk factor for asthma in adulthood (aOR 4.0, 95% CI 1.3-12.5).

CONCLUSION

Subjects with severe early wheezing have a 10-fold increase in the risk of adult asthma compared to an age-matched control group, adjusted for allergic rhinitis, gender, smoking and heredity.

'They said it was bronchiolitis; is it going to turn into asthma doctor?'

Acute bronchiolitis is a common paediatric disease of infancy. Its association with subsequent asthma development has puzzled clinicians and epidemiologists for decades. This article reviews the current state of knowledge regarding the role of acute bronchiolitis in the inception of asthma. There is little doubt that acute bronchiolitis is associated with an increased risk of recurrent wheezing throughout the primary school years although the direction of causality--i.e. whether bronchiolitis in infancy leads to asthma or it merely represents the first clinical presentation of predisposition to asthma--is uncertain. Existing evidence suggests that both host factors (e.g. prematurity, atopic predisposition) and acute viral infection characteristics (e.g. type of virus, severity) are operating in this relationship, perhaps with variable involvement in different individuals. Further clarification of these issues will help paediatricians provide evidence-based information regarding the long-term prognosis of this common disease to the families, and at the same time, it will facilitate prophylactic approaches and therapeutic strategies.

Risk of current asthma among adult smokers with respiratory syncytial virus illnesses in early life

RATIONALE

Risk of subsequent asthma-like symptoms after early-life lower respiratory illness (LRI) caused by respiratory syncytial virus (RSV) is increased during the first decade of childhood and diminished thereafter by adolescence.

OBJECTIVES

To determine the relation of early-life RSV-LRI on adult asthma-like symptoms and its interactive role with adult smoking.

METHODS

A total of 1,246 nonselected infants were enrolled at birth and prospectively followed. Virologically confirmed RSV-LRIs were assessed during the first 3 years of life. At age 22, 24, 26, and 29 years, current asthma and smoking behavior were evaluated by questionnaire. Peak flow variability was assessed at age 26 and expressed as amplitude % mean. A longitudinal analysis was used to investigate the relation of RSV-LRI and active smoking to adult outcomes.

MEASUREMENTS AND MAIN RESULTS

Neither RSV-LRI nor active smoking were directly associated with increased current adult asthma or peak flow variability. However, there was a significant interaction between RSV-LRI and active smoking in relation to current asthma (P for interaction = 0.004) and peak flow variability (P for interaction = 0.04). Among subjects with early RSV-LRI, those who actively smoked were 1.7 times more likely to have current asthma (95% confidence interval, 1.2-2.3; P = 0.003) and had greater amplitude % mean (10.0% vs. 6.4%; P = 0.02) than nonsmokers. Among subjects without early RSV-LRI, there was no difference in asthma risk or peak flow variability between active smokers and nonsmokers.

CONCLUSIONS

Smoking is associated with increased risk of having asthma in young adults who had RSV-LRI in early life but not among subjects without these illnesses.

A systematic review of predictive modeling for bronchiolitis

PURPOSE

Bronchiolitis is the most common cause of illness leading to hospitalization in young children. At present, many bronchiolitis management decisions are made subjectively, leading to significant practice variation among hospitals and physicians caring for children with bronchiolitis. To standardize care for bronchiolitis, researchers have proposed various models to predict the disease course to help determine a proper management plan. This paper reviews the existing state of the art of predictive modeling for bronchiolitis. Predictive modeling for respiratory syncytial virus (RSV) infection is covered whenever appropriate, as RSV accounts for about 70% of bronchiolitis cases.

METHODS

A systematic review was conducted through a PubMed search up to April 25, 2014. The literature on predictive modeling for bronchiolitis was retrieved using a comprehensive search query, which was developed through an iterative process. Search results were limited to human subjects, the English language, and children (birth to 18 years).

RESULTS

The literature search returned 2312 references in total. After manual review, 168 of these references were determined to be relevant and are discussed in this paper. We identify several limitations and open problems in predictive modeling for bronchiolitis, and provide some preliminary thoughts on how to address them, with the hope to stimulate future research in this domain.

CONCLUSIONS

Many problems remain open in predictive modeling for bronchiolitis. Future studies will need to address them to achieve optimal predictive models.

Increased asthma risk and impaired quality of life after bronchiolitis or pneumonia in infancy

BACKGROUND

Recent studies have revealed that adulthood asthma has its origin in early childhood.

AIM

The aim of the present study was to evaluate the prevalence of asthma and respiratory health-related quality of life in adults 30 years after hospitalization for bronchiolitis or pneumonia in infancy.

METHODS

Patients who were hospitalized for bronchiolitis or pneumonia at age under 24 months in 1981-1982 have been followed in repeated visits. In 2010, 48 of the 83 former patients with bronchiolitis (57.8%), 22 of the 44 former patients with pneumonia (50.0%), and 138 matched controls participated in the clinical study at the age of 28-31 years. The participants completed a structured questionnaire on respiratory symptoms, the Saint George's Respiratory Questionnaire (SGRQ), and underwent 2-week peak expiratory flow (PEF) monitoring. Asthma was defined as doctor-diagnosed and self-reported asthma based on doctor-prescribed medication for asthma, the presence of asthma-presumptive symptoms, and the results of home PEF monitoring.

RESULTS

Both doctor-diagnosed asthma (31.3% vs. 10.9% adjusted P = 0.002) and self-reported asthma (35.4% vs. 14.5% 0.003), as well as repeated on-demand use of bronchodilators (35.4% vs. 14.5% 0.002), and regular use of inhaled corticosteroids (20.8% vs. 8.7% 0.023) were more common in former bronchiolitis patients than in controls. Former bronchiolitis and pneumonia patients had higher total SGRQ scores than controls. The median scores were 5.4 (IQ(25-75) 0.0-14.7, P < 0.001) in bronchiolitis group, 4.9 (1.3-14.8, 0.012) in pneumonia group compared to controls 1.5 (0.0-6.0).

CONCLUSION

Hospitalization for bronchiolitis in infancy is associated with an increased risk of asthma, and an increased use of asthma medication in adulthood at the age of 28-31 years. Impaired respiratory health-related quality of life in adulthood as measured by the SGRQ is present after bronchiolitis and pneumonia in infancy.

Adolescent asthma after rhinovirus and respiratory syncytial virus bronchiolitis

BACKGROUND AND AIMS

Asthma risk is increased after bronchiolitis in infancy. Recent studies have suggested that the risk may be dependent on the causative virus. The aim of the study was to evaluate the asthma risk in adolescence in subjects hospitalized for rhinovirus or respiratory syncytial virus (RSV) bronchiolitis in infancy.

SUBJECTS AND METHODS

At the median age of 16.5 years, a questionnaire was sent to 96 study subjects hospitalized for bronchiolitis at <24 months of age and since then prospectively followed-up. Sixty-seven (70%) returned the fulfilled questionnaire. RSV and rhinovirus etiology of bronchiolitis had been studied in serum and respiratory samples obtained on admission in infancy. The occurrence of asthma was compared between former bronchiolitis patients and population controls recruited for this study in adolescence.

RESULTS

Doctor-diagnosed asthma was present in 30% of former bronchiolitis patients and in 5% of controls (OR 7.9, 95% CI 3.3-19.3). The respective figures for self-reported asthma were 64% and 11% (OR 14.7, 95% CI 7.2-30.0). Self-reported asthma was more common in the former rhinovirus than RSV patients (83.3% vs. 47.6%, P = 0.023, mixed infections included; 81.3% vs. 50%, P = 0.067, mixed infections excluded).

CONCLUSIONS

Patients hospitalized for RSV and rhinovirus bronchiolitis at <24 months of age had an increased asthma risk at 15-18 years of age compared with population controls. Within the former bronchiolitis group, the risk of self-reported asthma was higher after non-RSV versus RSV and after rhinovirus versus non-rhinovirus bronchiolitis.

Respiratory syncytial virus infection and recurrent wheezing in Chilean infants: a genetic background?

Respiratory syncytial virus (RSV) infection has been associated to recurrent wheezing, but pathogenic mechanisms are unclear. Interleukin-4/Interleukin-13 (IL-4/IL-13) pathway is involved in both conditions. A common host genetic susceptibility may exist in patients whom RSV will trigger severe illness and those who develop recurrent wheezing.

OBJECTIVE

To assess, by a candidate-gene approach, whether genetic polymorphisms in IL-4/IL-13 pathway are associated with RSV infection severity and its outcome in Chilean children. A cohort of 118 RSV-infected infants was analyzed and followed for one year. Severity of acute infection and later recurrent wheezing were characterized. Alleles and genotypes frequencies were determined for two SNP in each of the genes IL-4, IL-13 and IL-4Rα. Association tests and interaction analyses were performed. Enrollment included 60 moderate and 58 severe cases. Two SNP were found associated to severity during acute infection in IL-4Rα gene (Gln551Arg, Ile50Val). The follow up was completed in 71% of patients (84/118). Later recurrent wheezing was 54% in severe group, versus 31% in moderate cases (p=0.035). In relation to outcome, allele Ile50 in IL-4Rα was more frequent in patients with moderate disease and no wheezing outcome. A common protector genotype is proposed for Chilean children: IL-4Rα Ile/Ile.

CONCLUSION

Genetic variations in the host are associated to infection severity and outcome. A common genetic background might be influencing both pathologies.

Childhood infections and the risk of asthma: a longitudinal study over 37 years

BACKGROUND

Few studies have examined common childhood infections and adult asthma. We examined associations between childhood infectious diseases, childhood pneumonia, and current, persisting, and incident asthma to middle age.

METHODS

We analyzed data from the Tasmanian Longitudinal Health Study (TAHS). A history of pneumonia was ascertained from their parents when the TAHS participants were 7 years old. Measles, rubella, mumps, chickenpox, diphtheria, and pertussis were identified from school medical records. Associations with current, persisting, or incident asthma were examined using regression techniques.

RESULTS

Greater infectious diseases load was negatively associated with persisting asthma at all ages. Individually, pertussis (adjusted OR [aOR], 0.53; 95% CI, 0.28-1.00) was negatively associated with asthma persisting to age 13 years, chickenpox (aOR, 0.58; 95% CI, 0.38-0.88) was negatively associated with asthma persisting to age 32 years, and rubella was negatively associated with asthma persisting to ages 32 (aOR, 0.61; 95% CI, 0.31-0.96) and 44 years (aOR 0.53; 95% CI, 0.35-0.82). Pertussis was associated with preadolescent incident asthma (adjusted hazard ratio [aHR], 1.80; 95% CI, 1.10-2.96), whereas measles was associated with adolescent incident asthma (aHR, 1.66; 1.06-2.56). Childhood pneumonia was associated with current asthma at ages 7 (aOR, 3.12; 95% CI, 2.61-3.75) and 13 years (aOR, 1.32; 95% CI, 1.00-1.75), an association stronger in those without than those with eczema (aOR, 3.46; 95% CI, 2.83-4.24 vs aOR, 2.08; 95% CI, 1.38-3.12).

CONCLUSIONS

Overall, childhood infectious diseases protected against asthma persisting in later life, but pertussis and measles were associated with new-onset asthma after childhood. Measles and pertussis immunization might lead to a reduction in incident asthma in later life.

Need for a safe vaccine against respiratory syncytial virus infection

Human respiratory syncytial virus (HRSV) is a major cause of severe respiratory tract illnesses in infants and young children worldwide. Despite its importance as a respiratory pathogen, there is currently no licensed vaccine for HRSV. Following failure of the initial trial of formalin-inactivated virus particle vaccine, continuous efforts have been made for the development of safe and efficacious vaccines against HRSV. However, several obstacles persist that delay the development of HRSV vaccine, such as the immature immune system of newborn infants and the possible Th2-biased immune responses leading to subsequent vaccine-enhanced diseases. Many HRSV vaccine strategies are currently being developed and evaluated, including live-attenuated viruses, subunit-based, and vector-based candidates. In this review, the current HRSV vaccines are overviewed and the safety issues regarding asthma and vaccine-induced pathology are discussed.

Long term sequelae from childhood pneumonia; systematic review and meta-analysis

Background

The risks of long term sequelae from childhood pneumonia have not been systematically assessed. The aims of this study were to: (i) estimate the risks of respiratory sequelae after pneumonia in children under five years; (ii) estimate the distribution of the different types of respiratory sequelae; and (iii) compare sequelae risk by hospitalisation status and pathogen.

Methods

We systematically reviewed published papers from 1970 to 2011. Standard global burden of disease categories (restrictive lung disease, obstructive lung disease, bronchiectasis) were labelled as major sequelae. ‘Minor’ sequelae (chronic bronchitis, asthma, other abnormal pulmonary function, other respiratory disease), and multiple impairments were also included. Thirteen papers were selected for inclusion. Synthesis was by random effects meta-analysis and meta-regression.

Results

Risk of at least one major sequelae was 5.5% (95% confidence interval [95% CI] 2.8–8.3%) in non hospitalised children and 13.6% [6.2–21.1%]) in hospitalised children. Adenovirus pneumonia was associated with the highest sequelae risk (54.8% [39.2–70.5%]) but children hospitalised with no pathogen isolated also had high risk (17.6% [10.9–24.3%]). The most common type of major sequela was restrictive lung disease (5.4% [2.5–10.2%]) . Potential confounders such as loss to follow up and median age at infection were not associated with sequelae risk in the final models.

Conclusions

All children with pneumonia diagnosed by a health professional should be considered at risk of long term sequelae. Evaluation of childhood pneumonia interventions should include potential impact on long term respiratory sequelae.

Interaction between bronchiolitis diagnosed before 2 years of age and socio-economic status for bronchial hyperreactivity

OBJECTS

The prevalence of asthma has increased in recent decades globally. The objective of the present study is to elucidate whether hospitalization for bronchiolitis in infancy and low socioeconomic status interact for bronchial hyperreactivity during teenage years.

METHOD

We studied 522 children age 13-14 years attending schools in rural and urban areas to investigate the risk factors for bronchial hyperreactivity (BHR), defined as a provocation concentration of methacholine that causes a decrease of 20% (PC(20)) in forced expiratory volume within 1 second. Clinical examination, skin prick test, spirometry, and methacholine challenge were performed on all study subjects, who provided written consent. We used multivariate logistic regression to investigate the risk factors for BHR, and analyze the interaction between hospitalization for bronchiolitis in infancy and low socioeconomic status.

RESULTS

Forty-six (10.3%) positive BHR cases were identified. In the multivariate logistic analysis, as independent predictors of BHR, adjusted odds ratio of bronchiolitis diagnosed before 2 years of age in low income families was 13.7 (95% confidence interval, 1.4 to 135.0), compared to reference group, controlling for age, gender, parental allergy history, skin prick test, and environmental tobacco smoke (ETS) exposure. Interaction was observed between bronchiolitis before 2 years old and low socioeconomic status on children's bronchial hyperreactivity (p-interaction=0.025).

CONCLUSIONS

This study showed that bronchiolitis diagnosed before 2 years of age and low socioeconomic status interacted on children's bronchial hyperreactivity. Prevention of acute respiratory infection in early childhood in low socioeconomic status is important to prevent BHR as a precursor of asthma.

Pneumonia in the first 2 years of life, and asthma in preschool-age children

BACKGROUND

The relationship between viral bronchiolitis in early infancy and subsequent wheezing and asthma has been well established. The aim of the present cross-sectional study was to test the hypothesis that pneumonia severe enough to require hospitalization during the first 2 years of life could also be associated with asthma or asthma-like symptoms in pre-school children.

METHODS

Structured interviews were conducted with parents of children who were classified as exposed (n= 36) or non-exposed (n= 84), based on whether they were hospitalized with radiologically confirmed pneumonia during the first 2 years of life. The main outcomes were ever physician-diagnosed asthma, asthma-like symptoms and use of anti-asthmatic medications during the last 2 months and during the last 12 months.

RESULTS

The prevalence of ever physician-diagnosed asthma was higher in the exposed group compared with the non-exposed group (41.6% vs 22.6%, P= 0.01), with an adjusted prevalence ratio of 2.03 (95% confidence interval: 1.10-3.62). The exposed group had a trend toward a higher prevalence of asthma-like symptoms and use of anti-asthmatic medications during the last 2 months and during the last 12 months.

CONCLUSIONS

Radiologically confirmed pneumonia in the first 2 years of life may be associated with asthma or asthma-like symptoms in pre-school children.

Does a parent-reported history of pneumonia increase the likelihood of respiratory symptoms needing therapy in asthmatic children and adolescents?

BACKGROUND

Asthmatic children and adolescents attending outpatient clinics often have a history of pneumonia. Whether respiratory symptoms, lung function, and airway inflammation differ in asthmatic patients with and without a history of pneumonia remains controversial.

AIMS

To compare clinical, lung functional, and inflammatory variables in asthmatic outpatients with and without a history of pneumonia. Methods. In 190 asthmatic outpatients, aged 6-18 years, we assessed respiratory symptoms, lung function (flows, volumes, and pulmonary diffusion capacity, DLCO/VA), and atopic-airway inflammation as measured by the fractional concentration of exhaled nitric oxide (FE(NO)). A previous medical and radiological diagnosis of pneumonia was defined as "recurrent pneumonia" if subjects had at least three pneumonia episodes or two episodes within a year.

RESULTS

Of the 190 outpatients studied, 38 (20%) had a history of pneumonia. These patients had more frequent upper-respiratory symptoms, nighttime awakenings in the past 4 weeks, daily use of inhaled corticosteroids, and lower FE(NO) than the 152 asthmatic children without previous pneumonia (FE(NO): 20.6 ppb, 95% CI: 15.2-28.0 vs. 31.1 ppb, 95% CI: 27.0-35.8; p < .05). Of the 38 patients with previous pneumonia, 14 had recurrent pneumonia. Despite comparable lung volumes and flows, they also had lower DLCO/VA than asthmatic children with no recurrent pneumonia and asthmatic children without previous pneumonia (DLCO/VA%: 91.2 ± 11.3 vs. 108.5 ± 14.7 vs. 97.9 ± 18.6, p < .05).

CONCLUSION

Respiratory assessment in asthmatic children and adolescents with a history of pneumonia, especially recurrent pneumonia, often discloses symptoms needing corticosteroid therapy, and despite normal lung volumes and flows, mild reductions in the variables reflecting gas diffusion and atopic-airway inflammation (DLCO/VA and FE(NO)). Whether these respiratory abnormalities persist in adulthood remains an open question.

Rhinovirus-induced bronchiolitis and asthma development

Human rhinovirus (HRV) and respiratory syncytial virus (RSV) are commonly associated with bronchiolitis. The breaking point in the dominance is approximately 12 months--rhinovirus dominates in the older children. Predisposition may markedly increase the prevalence of HRV bronchiolitis. Especially, low interferon responses and atopy-related factors have been associated with HRV bronchiolitis. The former has been considered as a sign of poor antiviral defense, and the latter could be associated with atopic airway inflammation in wheezing children. Although recurrent wheezing is common after both RSV and HRV bronchiolitis, HRV bronchiolitis carries a markedly higher risk of persistent wheezing until 6 years of age and for childhood asthma. This association has been independent from atopy at 7.2 (median) years of age. The increased risk of asthma in adulthood after non-RSV bronchiolitis vs. RSV bronchiolitis in infancy (at the time when PCR was not available for HRV diagnosis) offers indirect evidence for the association between HRV bronchiolitis and chronic asthma.

The use of a neonatal mouse model to study respiratory syncytial virus infections

Respiratory syncytial virus (RSV) infection is the most significant cause of viral death in infants worldwide. The significant morbidity and mortality associated with this disease underscores the urgent need for the development of an RSV vaccine. The development of an RSV vaccine has been hampered by our limited understanding of the human host immune system, which plays a significant role in RSV pathogenesis, susceptibility and vaccine efficacy. As a result, animal models have been developed to better understand the mechanisms by which RSV causes disease. Within the past few years, a revolutionary variation on these animal models has emerged--age at time of initial infection--and early studies in neonatal mice (aged <7 days at time of initial infection) indicate the validity of this model to understand RSV infection in infants. This article reviews available information on current murine and emerging neonatal mouse RSV models.

Prevalence of asthma and bronchial hyperreactivity in Danish schoolchildren: no change over 10 years

AIM

To describe the point prevalence of current physician-diagnosed asthma and bronchial hyperreactivity (BHR) in 2001 among unselected Danish schoolchildren aged 6-17 years, compared with the prevalence from a similar study from 1990 to 1991.

METHODS

Cross-sectional study using parental questionnaire on asthma and respiratory symptoms combined with a 6-min free running test with peak expiratory flow rate (PEFR) measurement (n = 1051, response rate 89.3%). Results were compared with those of a similar study in the same area from 1990 to 1991. Main outcome measures were current physician-diagnosed asthma or BHR in children without physician-diagnosed asthma measured by either a decrease in lung function after standardized running test and/or variability in PEFR on home monitoring.

RESULTS

The prevalence of current physician-diagnosed asthma was 4.0% [95% confidence interval (CI) 2.7-5.3%] in 1990-1991 and 3.6% (95% CI 2.4-4.8%) in 2001. The prevalence of BHR was 3.2% (95% CI 2.0-4.4%) in 1990-1991 and 2.0% (95% CI 1.1-2.9%) in 2001. The combined prevalence was 7.2% (95% CI 5.4-8.9%) in 1990-1991 and 5.6% (95% CI 4.2-7.1%) in 2001.

CONCLUSION

The point prevalence of current physician-diagnosed asthma and BHR among unselected Danish schoolchildren aged 6-17 years was unchanged over 10 years between 1990-1991 and 2001.

Bacterial infections and pediatric asthma

Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis seem to have no role in asthma in children. Mycoplasma pneumoniae and Chlamydophila pneumoniae can induce wheezing and cause asthma exacerbations in children, and chronic Chlamydophila infections may even participate in asthma pathogenesis. However, studies have failed to show any benefits from antibiotics for incipient or stable pediatric asthma, as well as for asthma exacerbations in children. Exposure to antibiotics in infancy has been an independent risk factor of later asthma in many studies. A recent study applying molecular biology methods to lower airway samples provided preliminary evidence that lower airways are not sterile but have their own protective microbiota, which can be disturbed in lung diseases like asthma.

Viruses and asthma

Background

Viral respiratory infection has long been known to influence the occurrence of asthma exacerbations. Over the last 20 years much effort has been put into clarifying the role that viral respiratory infections play in the eventual development of asthma.

Scope of review

In this review we give a general background of the role of viruses in the processes of asthma exacerbation and asthma induction. We review recent additions to the literature in the last 3 years with particular focus on clinical and epidemiologic investigations of influenza, rhinovirus, bocavirus, respiratory syncytial virus, and metapneumovirus.

Major conclusions

The development of asthma emerges from a complex interaction of genetic predisposition and environmental factors with viral infection likely playing a significant role in the effect of environment on asthma inception. This article is part of a Special Issue entitled: Biochemistry of Asthma.

General significance

Further understanding of the role that viruses play in asthma exacerbation and inception will contribute to decreased asthma morbidity in the future. This article is part of a Special Issue entitled: Biochemistry of Asthma.

Respiratory morbidity in adulthood after respiratory syncytial virus hospitalization in infancy

A prospective >25-year follow-up study evaluated the outcome of patients hospitalized for respiratory syncytial virus (RSV) infection at <24 months of age. Questionnaires were sent to 51 study subjects and to population controls. Self-reported asthma was present in 30% of the former RSV patients, compared with 3.8% of controls. In adjusted analyses, RSV hospitalization was an independent risk factor of adulthood asthma.

Asthma in late adolescence--farm childhood is protective and the prevalence increase has levelled off

While the prevalence of and risk factors for asthma in childhood have been studied extensively, the data for late adolescence are more sparse. The aim of this study was to provide up-to-date information on the prevalence of and risk factors for asthma in the transitional period between childhood and adulthood. A secondary aim was to analyze whether the increase in asthma prevalence has levelled off. A large-scale, detailed postal questionnaire focusing on asthma and respiratory symptoms, as well as possible risk factors, was mailed to 30 000 randomly selected subjects aged 16-75 in Gothenburg and the surrounding western Sweden region. The present analyses are based on the responses from 1261 subjects aged 16-20 (560 men and 701 women). The prevalence of physician-diagnosed asthma was 9.5%, while 9.6% reported the use of asthma medicine. In the multivariate analysis, the strongest risk factors for physician-diagnosed asthma and other asthma variables were heredity for asthma and heredity for allergy, particularly if they occurred together. Growing up on a farm significantly reduced the prevalence of physician-diagnosed asthma and the likelihood of using asthma medication, OR 0.1 (95% CI 0.02-0.95). Smoking increased the risk of recurrent wheeze, long-standing cough, and sputum production. In conclusion, the prevalence of physician-diagnosed asthma and the use of asthma medication in the 16- to 20-yr age group support the notion that the increase in asthma prevalence seen between the 1950s and the 1990s has now levelled off. In line with the hygiene hypothesis, a farm childhood significantly reduced the likelihood of asthma. The adverse effects of smoking could already be seen at this young age.

Adulthood asthma after wheezing in infancy: a questionnaire study at 27 years of age

BACKGROUND

Wheezing in early childhood is a heterogeneous condition, the longterm prognosis varying from total recovery to chronic asthma. Though short-term outcome has been actively studied, there is lack of data on long-term outcome until adulthood. The aim of the study was to evaluate the prevalence and risk factors of asthma at 26-29 years of age after early-life wheezing.

METHODS

At the median age of 27.3 years (range 26.3-28.6), a questionnaire was sent to 78 study subjects hospitalized for wheezing at <24 months of age, and 59 (76%) answered. Asthma, allergy and weight status were compared with selected controls followed up from birth and with non-selected population controls recruited for this adulthood study.

RESULTS

Doctor-diagnosed asthma was present in 20% of the former bronchiolitis patients, compared with 5% in the two control groups (OR 2.1, 95% CI 0.3-17.9 vs selected controls; OR 5.2, 95% CI 1.7-15.8 vs nonselected controls). The respective figures for current self-reported asthma were 41% and 7-10% (OR 11.4, 95% CI 2.3-56.1 vs selected controls; OR 12.2, 95% CI 4.4-33.7 vs nonselected controls). Current allergic rhinitis and current smoking were significantly associated with asthma, but current overweight or obesity was not. In multivariate analyses, early-life wheezing was an independent risk factor of adulthood asthma.

CONCLUSION

An increased asthma risk in early-life wheezers continues, even after many symptom-free years at school age, at least until 27 years of age.

Long-term outcomes of early childhood wheezing

PURPOSE OF REVIEW

To summarize the currently available data on the long-term outcome until young adulthood after early childhood wheezing. Asthma and lung function abnormalities were evaluated, with special attention to early-life risk factors.

RECENT FINDINGS

In postbronchiolitis studies, 30-40% of the patients hospitalized for wheezing at less than 24 months of age have had asthma at 17-20 years of age. In the Tucson birth cohort study, the respective figure after wheezing at less than 36 months of age was 30% at 22 years of age. Relapses after many nonsymptomatic years have been common. In postbronchiolitis studies, lung function has been reduced in 31-36%, concerning also postbronchodilator measurements. Thus, the changes in airways seem to be structural, being present from infancy until adulthood, as found in the Tucson study. Parental asthma, repeated early-life wheezing and early passive smoking have been the most important early-life predictors of both adulthood asthma and lung function abnormalities.

SUMMARY

Early childhood wheezing increases the risk for asthma and lung function abnormalities in young adulthood. Not only chronic childhood asthma continuing until adulthood but also asthma beginning in early adulthood seems to have its origin in early childhood.

The severity-dependent relationship of infant bronchiolitis on the risk and morbidity of early childhood asthma

BACKGROUND

Infants hospitalized for bronchiolitis have a high rate of early childhood asthma. It is not known whether bronchiolitis severity correlates with the risk of early childhood asthma or with asthma-specific morbidity.

OBJECTIVES

We sought to determine whether a dose-response relationship exists between severity of infant bronchiolitis and both the odds of early childhood asthma and asthma-specific morbidity.

METHODS

We conducted a population-based retrospective birth cohort study of term healthy infants born from 1995-2000 and enrolled in a statewide Medicaid program. We defined bronchiolitis severity by categorizing infants into mutually exclusive groups based on the most advanced level of health care for bronchiolitis. Health care visits, asthma-specific medications, and demographics were identified entirely from Medicaid and linked vital records files. Asthma was ascertained at between 4 and 5.5 years of age, and 1-year asthma morbidity (hospitalization, emergency department visit, or oral corticosteroid course) was determined between 4.5 and 5.5 years among children with prevalent asthma.

RESULTS

Among 90,341 children, 18% had an infant bronchiolitis visit, and these infants contributed to 31% of early childhood asthma diagnoses. Relative to children with no infant bronchiolitis visit, the adjusted odds ratios for asthma were 1.86 (95% CI, 1.74-1.99), 2.41 (95% CI, 2.21-2.62), and 2.82 (95% CI, 2.61-3.03) in the outpatient, emergency department, and hospitalization groups, respectively. Children hospitalized with bronchiolitis during infancy had increased early childhood asthma morbidity compared with that seen in children with no bronchiolitis visit.

CONCLUSION

To our knowledge, this is the first study to demonstrate the dose-response relationship between the severity of infant bronchiolitis and the increased odds of both early childhood asthma and asthma-specific morbidity.

Bronchiolitis: age and previous wheezing episodes are linked to viral etiology and atopic characteristics

BACKGROUND

: Diagnostic criteria for bronchiolitis are variable.

OBJECTIVE

: To study how the risk factors for recurrent wheezing and asthma vary by different definitions of bronchiolitis.

METHODS

: Viral etiology and atopic characteristics were studied in 259 hospitalized wheezing children (median age, 14 months; range, 0-36 months). The data were analyzed according to age (<6, <12, <24 and <36 months) and whether they had a history or no history of a previous wheezing episode. Sixteen viruses were detected by conventional and molecular methods. Atopic characteristics included the presence of eczema, specific and total IgE responses, blood eosinophil count, and modified asthma predictive index.

RESULTS

: Evidence of respiratory virus infection was found in 93% of the cases and allergic sensitization in 26% of the cases. Rhinovirus infections and atopic characteristics (sensitization, blood eosinophil count, and modified asthma predictive index) increased by age and were significantly more common in children with recurrent wheezing episodes than in first-time wheezers in age categories of <24 and <36 months (P < 0.05 for all).

CONCLUSIONS

: In children with bronchiolitis, 2 clinical factors, age and number of previous wheezing episodes, are linked to inflammatory (atopy-related factors) and virologic risk factors of asthma (rhinovirus-associated disease). According to current US and UK guidelines, bronchiolitis includes wheezing children <24 months of age. Our observations suggest that the clinical definition should include only children with their first episode of wheezing.

Early exposure and sensitization to cat and dog: different effects on asthma risk after wheezing in infancy

Birth cohort studies have suggested that early exposure to furred pets protects from later asthma and allergy. The aim of the present study was to evaluate the association between exposure or sensitization to cat or dog in infancy, and later asthma and allergy assessed at the median ages of 4.0, 7.2 and 12.3 yr, in children who have wheezed at <24 months of age. Exposure to cat and dog in infancy was assessed by interviewing the parents. The child was considered as sensitized, if the allergen-specific IgE to cat or to dog was >or=0.35 kU/l, or if there was a positive skin test response. When the 20 children with persistent childhood asthma (doctor-diagnosed asthma at all three control visits) were compared with the other 61 children, an early exposure to dog (OR = 0.14, p = 0.034)) decreased the asthma risk and an early sensitization to cat (OR = 5.92, p = 0.008) and dog (OR = 9.33, p = 0.001) increased the asthma risk. There were less cat and dog keeping in atopic families and the effect of sensitization was, but the effect of exposure was not, robust to adjustments in multivariate analyses. The present study demonstrates, in a long-term follow-up after early wheezing, that early sensitization to cat and dog increases the risk of later asthma but early exposure to cat or dog has no such effect. Dog keeping was less frequent in atopic families, which may explain that the protective effect of early exposure to dog was lost in multivariate analyses.